How can I rewrite the following to avoid a "Nesting Blocks" error?

Question

The following code generates

SystemError: too many statically nested blocks

import csv
with open('complexdatset.csv','r'), open ('back.csv','w'), open ('buffer_overflow.csv','w'), open ('ftp_write.csv','w'), open ('guess_passwd.csv','w'), open ('imap.csv','w'), open ('ipsweep.csv','w'), open ('land.csv','w'), open ('loadmodule.csv','w'), open ('multihop.csv','w'), open ('neptune.csv','w'), open ('nmap.csv','w'), open ('perl.csv','w'), open ('phf.csv','w'), open ('pod.csv','w'), open ('portsweep.csv','w'), open ('rootkit.csv','w'), open ('satan.csv','w'), open ('smurf.csv','w'), open ('spy.csv','w'), open ('teardrop.csv','w'), open ('warezclient.csv','w'), open ('warezmaster.csv','w') as fin, back, buffer_overflow, ftp_write, guess_passwd, imap, ipsweep, land, loadmodule, multihop, neptune, nmap, perl, phf, pod, portsweep, rootkit, satan, smurf, spy, teardrop, warezclient, warezmaster:
    writer0 = csv.writer(back, delimiter=',')
    writer1 = csv.writer(buffer_overflow, delimiter=',')
    writer2 = csv.writer(ftp_write, delimiter=',')
    writer3 = csv.writer(guess_passwd, delimiter=',')
    writer4 = csv.writer(imap, delimiter=',')
    writer5 = csv.writer(land, delimiter=',')
    writer6 = csv.writer(loadmodule, delimiter=',')
    writer7 = csv.writer(multihop, delimiter=',')
    writer8 = csv.writer(neptune, delimiter=',')
    writer9 = csv.writer(nmap, delimiter=',')
    writer10 = csv.writer(perl, delimiter=',')
    writer11 = csv.writer(phf, delimiter=',')
    writer12 = csv.writer(pod, delimiter=',')
    writer13 = csv.writer(portsweep, delimiter=',')
    writer14 = csv.writer(rootkit, delimiter=',')
    writer15 = csv.writer(satan, delimiter=',')
    writer16 = csv.writer(smurf, delimiter=',')
    writer17 = csv.writer(spy, delimiter=',')
    writer18 = csv.writer(teardrop, delimiter=',')
    writer19 = csv.writer(warezclient, delimiter=',')
    writer20 = csv.writer(warezmaster, delimiter=',')
    for row in csv.reader(fin, delimiter=','):
        if row[41] == 'back':
            writer0.writerow(row)
        elif row[41] == 'buffer_overflow':
            writer1.writerow(row)
        elif row[41] == 'ftp_write':
            writer2.writerow(row)
        elif row[41] == 'guess_passwd':
            writer3.writerow(row)
        elif row[41] == 'imap':
            writer4.writerow(row)
        elif row[41] == 'land':
            writer5.writerow(row)
        elif row[41] == 'loadmodule':
            writer6.writerow(row)
        elif row[41] == 'multihop':
            writer7.writerow(row)
        elif row[41] == 'neptune':
            writer8.writerow(row)
        elif row[41] == 'nmap':
            writer9.writerow(row)
        elif row[41] == 'perl':
            writer10.writerow(row)
        elif row[41] == 'phf':
            writer11.writerow(row)
        elif row[41] == 'pod':
            writer12.writerow(row)
        elif row[41] == 'portsweep':
            writer13.writerow(row)
        elif row[41] == 'rootkit':
            writer14.writerow(row)
        elif row[41] == 'satan':
            writer15.writerow(row)
        elif row[41] == 'smurf':
            writer16.writerow(row)
        elif row[41] == 'spy':
            writer17.writerow(row)
        elif row[41] == 'teardrop':
            writer18.writerow(row)
        elif row[41] == 'warezclient':
            writer19.writerow(row)   
        elif row[41] == 'warezmaster':
            writer20.writerow(row)

My question is why does it generate this error? I searched online but all the examples had loops nested 20 levels deep. I don't have the file I/O nested that much at all. I just make very extensive checks for one variable and create files 2 levels deep. My goal was to create individual '.csv' files for each of the different classes of this particular dataset. Also is there a better way to rewrite this so I can avoid the SystemError?

score 0 · Answer 1 · answered Oct 28 '16 at 08:39

use a dictionary for options:

import csv



with open('complexdatset.csv','r'), open ('back.csv','w'), open ('buffer_overflow.csv','w'), open ('ftp_write.csv','w'), open ('guess_passwd.csv','w'), open ('imap.csv','w'), open ('ipsweep.csv','w'), open ('land.csv','w'), open ('loadmodule.csv','w'), open ('multihop.csv','w'), open ('neptune.csv','w'), open ('nmap.csv','w'), open ('perl.csv','w'), open ('phf.csv','w'), open ('pod.csv','w'), open ('portsweep.csv','w'), open ('rootkit.csv','w'), open ('satan.csv','w'), open ('smurf.csv','w'), open ('spy.csv','w'), open ('teardrop.csv','w'), open ('warezclient.csv','w'), open ('warezmaster.csv','w') as fin, back, buffer_overflow, ftp_write, guess_passwd, imap, ipsweep, land, loadmodule, multihop, neptune, nmap, perl, phf, pod, portsweep, rootkit, satan, smurf, spy, teardrop, warezclient, warezmaster:
    writer0 = csv.writer(back, delimiter=',')
    writer1 = csv.writer(buffer_overflow, delimiter=',')
    writer2 = csv.writer(ftp_write, delimiter=',')
    writer3 = csv.writer(guess_passwd, delimiter=',')
    writer4 = csv.writer(imap, delimiter=',')
    writer5 = csv.writer(land, delimiter=',')
    writer6 = csv.writer(loadmodule, delimiter=',')
    writer7 = csv.writer(multihop, delimiter=',')
    writer8 = csv.writer(neptune, delimiter=',')
    writer9 = csv.writer(nmap, delimiter=',')
    writer10 = csv.writer(perl, delimiter=',')
    writer11 = csv.writer(phf, delimiter=',')
    writer12 = csv.writer(pod, delimiter=',')
    writer13 = csv.writer(portsweep, delimiter=',')
    writer14 = csv.writer(rootkit, delimiter=',')
    writer15 = csv.writer(satan, delimiter=',')
    writer16 = csv.writer(smurf, delimiter=',')
    writer17 = csv.writer(spy, delimiter=',')
    writer18 = csv.writer(teardrop, delimiter=',')
    writer19 = csv.writer(warezclient, delimiter=',')
    writer20 = csv.writer(warezmaster, delimiter=',')
    options = {
        'back': writer0.writerow,
        'buffer_overflow': writer1.writerow,
        'ftp_write' :  writer2.writerow,
        'guess_passwd' :  writer3.writerow,
        'imap' :writer4.writerow,
        'land':writer5.writerow,
        'loadmodule':writer6.writerow,
        'multihop':writer7.writerow,
        'neptune':writer8.writerow,
        'nmap':writer9.writerow,
        'perl':writer10.writerow,
        'phf':writer11.writerow,
        'pod':writer12.writerow,
        'portsweep':writer13.writerow,
        'rootkit':writer14.writerow,
        'satan':writer15.writerow,
        'smurf':writer16.writerow,
        'spy':writer17.writerow,
        'teardrop':writer18.writerow,
        'warezclient':writer19.writerow,
        'warezmaster':writer20.writerow,
    }
    for row in csv.reader(fin, delimiter=','):
        if row[41] in options.keys() :
            options[row[41]](row)

Sorry. This still generates the same error. Would this mean I would need to use a dictionary for both the csv.writer and the options? — user3255824, Nov 08 '16 at 20:56

score 0 · Answer 2 · edited May 23 '17 at 12:34

0

Your opens are in essence nested, and you have 23 of them. You can use a contextlib.ExitStack() (contextlib2 in Python 2.7) to contain multiple contexts, thereby avoiding nesting.

See How to open more than 19 files in parallel (Python)? for some good examples.

edited May 23 '17 at 12:34

Community

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answered Apr 26 '17 at 00:40

leekaiinthesky

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How can I rewrite the following to avoid a "Nesting Blocks" error?

2 Answers2